23andMe and You



Who am I? If you have ever asked this question to yourself, then you might have considered the genetic testing services that genomics company 23andMe offer. Claiming to “explain your DNA,”, this company is the most popular of its kind with over 2 million customers. They offer two main services: ancestry services and a more expensive health service. The popularity of genetic testing services is apparent; however, are these services worth a sample of your saliva?

My fascination with genetic testing started not only because I saw the 23andMe testing kit on sale over the holidays. It began with a curiosity about what makes me, me, – as well as a 7th grade biology lecture about pea plants. Gregor Mendel, the father of genetics, probably couldn’t have imagined that his pea plant experiments would snowball over the years and lead to one of the fastest growing fields in science (1). The discovery of DNA happened 88 years after the publication of Mendel’s experiment (1). From then, it took 43 years to clone the first mammal, Dolly the sheep (2). By comparison, it only took 13 years for scientists to completely map every single one of the 3.2 billion nucleotide bases of the human genome.

The techniques that helped map the human genome are similar to those that genomic companies use. The molecular genetic technique that 23andMe uses is called genotyping, which is “‘an analysis that looks at hundreds of thousands of specific locations on your DNA that vary between individuals and associated with certain conditions, traits or ancestry” (6). A report in 2013 by the National Institute of Health (NIH) briefly describes how genetic tests can be used to assess over 2,000 rare and common conditions (7).

The contents of the 23andMe saliva collection kit. (Source)


However, 23andMe directly states that their test cannot be used to determine the status of their customers’ health. The company does not use the combination of conventional cytogenetic, molecular cytogenetic, and molecular genetic techniques that is necessary for determining the presence of chromosomal abnormalities. Therefore, health information taken from genetic testing services should not be used for self-diagnosis.

The US Food and Drug Administration (FDA), which regulates the validity of genetic tests, attempted to stop genomics companies from performing these health-related direct-to-consumer genetic tests in 2013 (8). The FDA sent a warning letter to genetic testing companies to immediately halt providing health information, because the genetic testing process did not meet FDA standards (8). Genomic testing registries use single nucleotide polymorphisms (SNPs) within DNA and use a microarray called an SNP chip to decode the genome (8). DNA is like a scantron test and these companies feed it into a machine that marks whether or not the DNA matches their answer key. The scantron is the genome, each answer bubbled in is the SNP, and the answer key is the SNP chip. Each right and wrong answer represents the variation in DNA which indicates where there is a potential trait that can be identified. An article published in the American Journal of Human Genetics found that the gene-association studies that use this method are rarely statistically significant in assessing health: “To date, the scientific evidence for most associations between genetic variants and disease risk is insufficient to support useful applications.” (9) This means that, at least in regards to your health, you should save your money and keep getting medical advice from your doctors.

The other appeal of genetic testing services is its potential to describe your ancestry. The 23andMe website claims that it will compare an individual’s DNA to DNA from around the world. According to their ancestry composition report, there are only 31 populations that are represented in their database. This means that if the sequences in an individual’s DNA are not represented by any of the already existing populations in their database, the results may be inconclusive in determining ancestry. To put it more simply, imagine that populations were like flavors of ice cream. You are in Baskin Robbins and there are the usual 31 flavors of ice cream to choose from. You walk up to the counter, but to your surprise there is a 32nd flavor! When the clerk describes the taste, he first compares it to the existing 31 flavors. However, the 32nd flavor has a special ingredient not found in any of the other flavors. “What is that special ingredient?” you might ask; the clerk would reply,  “I have no idea.” In other words, your DNA might contain a special ingredient not found in any of the 31 populations listed by 23andMe. Although you pay the company to determine where your ancestors came from, your results may be inconclusive in determining your ethnicity.

So, is it worth it?

A satisfied customer of 23andMe and a postdoctoral fellow at Chapman University, Charlene McCord, shared with me that she had very little information about her ancestry due to her having a closed adoption. She sought the ancestral genetic testing service because of a lifelong curiosity to find out, “What am I?”. Charlene shared that she was about 30% Scandinavian and about 25% British and Irish. Not only did she find the answers she was seeking, she was also able to contribute to research.

The DNA samples that customers provide can be used for scientific research, but only with their consent. This is important to understand before accessing these services because individuals might not have a say in what studies their DNA gets to be a part of, even if identities are kept anonymous. Therefore, before putting a kit in an online cart, you should read the recent publications found on their website to get an idea of the research that you might be contributing to.

There are plenty of companies that provide direct-to-consumer genetic tests. These kits are easy to use and affordable which makes their popularity understandable. Consumers should be aware that the results of an ancestry test might not be as accurate as the sites portray and absolutely no health diagnoses should be derived from them. However, these genetic testing registries can be useful to some people and help educate them about their DNA. But remember that before you send your saliva sample to their lab, make sure you know what their lab is going to do with it after they send you your report.



  1. https://www.genome.gov/pages/education/genetictimeline.pdf
  2. http://www.animalresearch.info/en/medical-advances/timeline/cloning-dolly-the-sheep/
  3. https://www.hindawi.com/journals/bmri/2015/461524/
  4. http://onlinelibrary.wiley.com/doi/10.1038/npg.els.0002650/abstract
  5. https://www.ncbi.nlm.nih.gov/pubmed/15557693
  6. https://www.23andMe.com/genetic-science/
  7. https://report.nih.gov/nihfactsheets/ViewFactSheet.aspx?csid=43
  8. https://poseidon01.ssrn.com/delivery.php?ID=016013006095020018091122115112115029038020028004063010126024124075031119125031104124036118001032056056002117065119069098024092041061069087049097111085093082119110086017066015004085004076111109027002091115122080009124101091009100028073092115065008084093&EXT=pdf
  9. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2427295/